\section{Introduction}
\label{sec:intro}
One of our challenges is understanding each other. Alghouth using internet as a social interaction mediam was suggested from its birth, how to effectively communicate, share knowleges and collaborae on inernet still haunts researches. In addition, new technologies, especially mobile device and  On the other hand, as the World Wide Web(WWW) melt into everyone's daily activities, how to let web sites provide user-driven contents and customized services became a main concern of both acadamic and commerical filed. ``who are you'' and ``who do you connect with'' are two key questions to be answered for better internet services. It is known for long time that WWW has self-organized social property, a formal usage of ``social network'', a concept quoted from sociology, became popular in internet industry was not until emerging of serval success social network platforms after 2000. some evangelism web sites \footnote{sixdegree.com 1997}